Argentina (9) 15
Penalties: Sanchez 5
Australia (19) 29
Tries: Simmons, Ashley-Cooper 3
Conversions: Foley 3
Australia held off a swashbuckling Argentina display to set-up an all-star Rugby World Cup final meeting with defending champions New Zealand following a gutsy victory at Twickenham. Adam Ashley-Cooper scored a hat-trick to underpin a Wallaby performance which lurched from the sublime to the ridiculous amid a Pumas showing which was full of enterprise but devoid of the structure required to deny their opponents a fourth final appearance.
Michael Cheika's side led 19-9 at the interval after Rob Simmons' intercepted try, the fastest of the 2015 tournament, and Ashley-Cooper's double but Argentina were unperturbed and a showing littered with thrilling offloads and mercurial footwork had them threatening to reach their first ever World Cup final. But Australia's breakdown prowess and workmanlike defence saw them outlast their ill-disciplined Rugby Championship counterparts, with Ashley-Cooper's late effort confirming the win. It was another game however where the performance of the referee, Wayne Barnes, will be scrutinised.
Victory sees Australia set-up a final against the All Blacks - the two only unbeaten teams - for the first time in the competition's history while Argentina take on South Africa in the third/fourth place play-off. But Daniel Hourcade's side will be wondering what if after butchering opportunities to stage an almighty upset.
Eight years on from breaking new ground at the showcase tournament with a third place finish, Argentina were looking to go one better than in 2007 and reach a first ever World Cup final. Hourcade's team were seeking to repeat the heroics which saw them dumped out Ireland in the last eight and book a rematch with finalists New Zealand, who defeated them in the pool stage.
The daunting obstacle between them and history was an Australia side who'd had the fortuitousness of their passage into the semi-final confirmed by World Rugby's overruling of Craig Joubert's decision to award the two-time winners a penalty in the penultimate minute against Scotland. Cheika's side may have ridden their luck but they were boosted by the return of turnover specialist David Pocock and full-back Israel Folau, both of whom would enhance their attacking threat.
Champions on British soil from 1991 and 1999, Australia had never lost a World Cup match at Twickenham in four attempts. Furthermore, with one defeat to Argentina in the last 11 meetings spanning 18 years, they were fancied to maintain their 100% record and reach the record-equalling fourth final.
And the favourites amid a typically frenetic and open start strolled into the ascendency with an early lead as Nicolas Sanchez was guilty of looking inside mid-way his own half and Simmons snatched the interception before going over. The Pumas fly-half made amends immediately with a penalty after Marcelo Bosch broke through, but another error from Sanchez left Argentina facing a mountain to climb after just 10 minutes.
The Toulon half-back tapped and ran the ball from a 22-drop out, only to knock-on and the turnover of possession directly led to the second try. From the subsequent scrum Bernard Foley threw an audacious pass out wide which took out three Argentina defenders and allowed Ashley-Cooper to run in untracked to score.
Hopes Argentina had of staging a first half comeback were initially boosted by a penalty won from a scrum against the head - a blow for the Argentine-coached Australian front row marshalled by Mario Ledesma - which Sanchez kicked successfully but the challenge facing them soon grew. Tomas Lavanini was sin-binned for leading with the shoulder in a tackle on Folau, despite the inconclusive video evidence, and it handed the initiative back to Australia.
With Juan Imhoff having already been replaced, captain Agustin Creevy followed and the continual losses eventually took their tole as Australia ran in a third try. Argentina again attempted a foray from inside their own half and upon winning another turnover, Matt Giteau sprayed a pass out to Ashley-Cooper, who doubled his tally with ease.
Despite being continually punished for their cavalier approach Argentina continued to probe and it almost paid off with their first try in the twilight of the first half but after Santiago Cordero ghosted through, Joaquin Tuclet misjudged Juan Martin Hernandez's offload and the chance was squandered.
Hernandez became the third Argentina injury victim at the start of the second half but the Pumas came within a score of Australia as a third penalty won in the scrum was kicked by Sanchez. But the South American's exit strategy continued to be their undoing and another uncertain clearance allowed Foley to reestablish the 10-point lead.
The breaks from the Argentina backs were however relentless and amid some curious officiating from Barnes which saw decisions go against both sides, Sanchez kicked his fifth penalty from some more good field position. But Australia would go on to book their place in the final against the All Blacks as after Drew Mitchell evaded a host of tired-looking tackles, his pass out to Ashley-Cooper saw him complete his treble and send his side through.
Argentina: 15 Joaquin Tuculet, 14 Santiago Cordero, 13 Marcelo Bosch, 12 Juan Martin Hernandez, 11 Juan Imhoff, 10 Nicolas Sanchez, 9 Martin Landajo, 8 Leonardo Senatore, 7 Juan Martin Fernandez Lobbe, 6 Pablo Matera, 5 Tomas Lavanini, 4 Guido Petti, 3 Ramiro Herrera, 2 Agustin Creevy (c), 1 Marcos Ayerza
Replacements: 16 Julian Montoya, 17 Lucas Noguera Paz, 18 Juan Figallo, 19 Matias Alemanno, 20 Facundo Isa, 21 Tomas Cubelli, 22 Jeronimo de la Fuente, 23 Lucas Gonzalez Amorosino.
Australia: 15 Israel Folau, 14 Adam Ashley-Cooper, 13 Tevita Kuridrani, 12 Matt Giteau, 11 Drew Mitchell, 10 Bernard Foley, 9 Will Genia, 8 David Pocock, 7 Michael Hooper, 6 Scott Fardy, 5 Rob Simmons, 4 Kane Douglas, 3 Sekope Kepu, 2 Stephen Moore (c), 1 James Slipper
Replacements: 16 Tatafu Polota-Nau, 17 Toby Smith, 18 Greg Holmes, 19 Dean Mumm, 20 Ben McCalman, 21 Nick Phipps, 22 Matt Toomua, 23 Kurtley Beale